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No. 325,790. I Patented Sept. 8, 1 885.

. UNITED STATES PATENT ()Frrcn.

BENTON ELMORE, OF SHASTA, CALIFORNIA.

SCR EW-PLATE.

SPECIFICATION forming part of Letters Patent No. 325,790, dated September 8, 1885,

Application filed June fl), 1885. (No model.)

To all whom it may concern:

Be it known that I, BENTON ELMORE, of Shasta city, Shasta county, State of California, have invented an Improvement in Screw- Plates; and I hereby declare the following to be a full, clear, and exact description of the same.

Myinvention relates to a novel construction of screw-cutting plates.

It consists of two parallel jaws or plates having the adjacent faces grooved'and formed so as to cut threads upon any bolt or piece of metal which may be inserted between them, the opposite end of each plate having transverse extensions, and levers are fulcrumed to the plates and to these extensions, so that the plates may be opened or closed by the movement of the levers. Strong springs are so attached as to press upon the backs of the plates and force them together,and adj usting-screws determine the space which shall be left between them while at work.

Referring to the accompanying drawings for a more complete explanation of my invention, Figure 1 is a view showing the plates with their transverse extensions and the springs. Fig. 2 shows the completed mechanism with the levers and regulatingscrews.

A A are two plates of metal having their adjacent faces threaded,the screw-threads being of proper size and pitch so that they perform the work of the dies which are used in ordinary screw-plates. One end of each of these plates A is formed with or has secured to it at right angles an extension, F, the extension on one passing by the opposite end of the other plate, as shown, and they extend also a short distance beyond the backs of the plates.

A strong spring, B, has one end secured in the extension of one of the plates, this spring passing over the back of the plate, and having the other end fitted to slide through an opening in that part of the extension of the opposite plate which projects beyond the end of the first one. A similar spring is fitted to press upon the back of the opposite plate in a like manner.

C G are adjusting or gage screws,which pass through the plates near the end, so that the point of one screw may abut against the inner ends of the opposite plate. By adj usting these screws the plates will be held as far apart as may be desired, so that in cutting a thread upon the bolt, if it be desired, only one half of the depth of the thread may be cut at the first operation, and it may be completed at the second, as might be necessary sometimes on account of the poor quality of the iron.

In order to separate the plates A against the pressure of the springs, for the purpose of admitting the bolt or article upon which the thread is to be cut, levers D are fulcrumed upon the transverse portions E, the inner end of each lever being pivoted, to the free end of the plate which stands opposite to it. By pulling the right-hand lever toward the person, and pushing the left-hand leverrin the opposite direction, the plates may be opened or separated so as to be applied to the bolt upon which the thread is to be cut. The plates are then allowed to close upon the bolt, and the pressure of the springs holds them with su'flicient force so that they will cut a thread to the desired depth, this being regulated by the gage-screws C before described.

As many openings may be made in the adj acent faces of the plates as may be desiredas, for instance, two sets of plates may be used, one having sizes numbered 10, 12, 14:, and 16, and the other 12, 14,16, and 18, these covering about all the threads which are generally used or needed in the ordinary blacksmiths shop.

The whole device is very simply made, the parts being all plain work, and being only eight in number.

The jaws or plates may be separated whenever the thread is finished, at whateverpoint they may be upon the bolt,without waiting to run them off, and they will never clog or strip the thread off the bolt.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The screw-plates having their adjacent faces threaded, and having transverse extensions at their opposite ends, as shown, in combination with the springs B, passing over the backs of the plates, having one end attached, and the other sliding loosely in the opposite extensions, substantially as and for the purpose herein described.

ICO

2. The parallel plates having their adjacent I in combination with the levers D, fulcrunied faces threaded and the transverse extensions in the transverse extensions, and connected at their opposite ends, in combination with with opposite ends of the plates A, substanthe compressing-springs B,attached as shown, tially as herein described. 5 and the gage-screws O,snbstantially as herein In witness whereof I have hereunto set my 15 described. hand. a

3. The plates having their adjacent faces BENTON ELMORE. threaded, and having the transverse exten- Vitnesses: sions from their opposite ends, with the gage- ISAAC SIMON, 1o screws and compressing springs 13, as shown, FRED GROTFEND. 

